06/04/14: Mark Castellano enters the courtroom before closing arguments of the Mark Castellano trial at the Harris County Criminal Courthouse 184th State District Court in Houston, Texas.

Photo: Thomas B. Shea, For The Chronicle

06/04/14: Mark Castellano enters the courtroom before closing...

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Family of Michelle Warner react as accused killer Mark Augustin Castellano, 39, is walked into the courtroomin the Harris County Criminal Justice Center for opening statements Tuesday, May 27, 2014, in Houston.
Castellano is accused of killing Warner, his girlfriend, and burying her body in an oil field between Odessa and Midland in 2012. Police said he confessed to killing a woman he loved greatly yet hated terribly. Days before confessing, he told police and Dr. Phil, on a segment taped for the national television show, that she walked out of their Houston apartment after a fight and disappeared.

Photo: Johnny Hanson, Houston Chronicle

Family of Michelle Warner react as accused killer Mark Augustin...

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The family of Michelle Warner listens to opening arguments during the trial of Mark Augustin Castellano, who is accused of murdering his girlfriend, Michelle Warner.

Photo: Johnny Hanson / Houston Chronicle

The family of Michelle Warner listens to opening arguments during...

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Mark Augustin Castellano, right, next to his attorneys during opening arguments.he is accused of murdering his girlfriend, Michelle Warner, Tuesday, May 27, 2014.

Photo: Johnny Hanson / Houston Chronicle

Mark Augustin Castellano, right, next to his attorneys during...

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Mark Augustin Castellano, right, next to his attorney Jacquelyn Carpenter during opening arguments.he is accused of murdering his girlfriend, Michelle Warner.

Photo: Johnny Hanson / Houston Chronicle

Mark Augustin Castellano, right, next to his attorney Jacquelyn...

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The family of Michelle Warner reacts as Mark Augustin Castellano is walked into the courtroom in the Harris County Criminal Justice Center for opening statements Tuesday. He is accused of killing Warner, his girlfriend, and burying her body in West Texas.

Photo: Johnny Hanson

The family of Michelle Warner reacts as Mark Augustin Castellano is...

During closing arguments Wednesday, prosecutors said Castellano choked Warner to death while their 3-year-old son was in the next room, then hid her body in the closet.

He then drove the child to Odessa to stay with his parents. Castellano later told Houston police that he returned to Houston, put Warner's body in a plastic container and drove back to West Texas, where he left the body in a shallow grave near Midland.

Days later, after repeatedly lying to police and family, Castellano agreed to an interview with Dr. Phil on a segment taped for the nationally syndicated TV show. He told the talk show host that Warner walked out of their Houston apartment after a fight and disappeared.

Castellano gave several versions of what happened, including that he snapped her neck and choked her. He also told investigators where to find her body.

He faces a maximum sentence of life in prison. The sentencing phase will continue Friday.